Relationship Between Bile Composition and Gallstone Formation in Squirrel Monkeys

Abstract

Squirrel monkeys (Saimiri sciureus) fed a commercial diet (group 1) do not develop gallstones and their gallbladder biles have low concentrations of cholesterol relative to bile acids and phospholipids. On the other hand, monkeys fed a semipurified diet containing corn oil and no cholesterol (group 2) occasionally had gallstones and a higher concentration of cholesterol. Monkeys on semipurified diets containing butter and cholesterol (group 3) had a high incidence of gallstones and very high concentrations of cholesterol relative to phospholipid and bile acids. The animals in group 3 with gallstones had higher cholesterol concentrations in bile than monkeys in that group without stones. The presence of gallstones in individuals was predicted from gallbladder bile compositions using any one of several indices of the maximum level of cholesterol that could be stabilized in micellar forms. Regardless of whether stones were present, concentrations of cholesterol relative to bile acids and phospholipids were higher in hepatic than in gallbladder bile. Gallbladder and hepatic biles of monkeys with gallstones and abnormal bile composition contained flat, rhomboid microscopic crystals. Occasionally, crystals as large as 500 p were in the gallbladder biles. Deoxycholic acid was present in relatively low concentrations in the biles of animals from group 1 and of those monkeys from group 3 that had gallstones, although deoxycholic and lithocholic acids predominated in the large intestine of all animals. The ratios of taurocholic to taurochenodeoxycholic acid in gallbladder biles were highest in the monkeys of group 3 with stones. The pool size of taurocholic acid and total bile acids were much higher in monkeys from group 1 than in the other monkeys.